# Claude Fable 5.1 vs Claude Opus 4.5

Claude Fable 5.1 is one of Anthropic's newest models and Claude Opus 4.5 an earlier one, so this is also what moving up costs or saves. Claude Opus 4.5 is the cheaper of the 2: for the same tokens, 3 read for each 1 written, Claude Fable 5.1 costs 2 times as much. Below are both price lists, what 8 everyday jobs cost a month on each, and how many tokens the same text takes on each, which can change the answer.

- Page, with a calculator for your own job: https://tecyfy.com/prices/compare/claude-fable-5-1-vs-claude-opus-4-5
- Makers: Claude Fable 5.1 from Anthropic, Claude Opus 4.5 from Anthropic

## Price per million tokens, in US dollars

| | Claude Fable 5.1 | Claude Opus 4.5 |
| --- | --: | --: |
| Input | $10 | $5 |
| Cached input | $0.25 | $0.50 |
| Cache write | $12.50 | $6.25 |
| Output | $50 | $25 |
| Blend, 3 read for each 1 written | $20 | $10 |
| Batch input | $5 | $2.50 |
| Batch output | $25 | $12.50 |
| Context window, tokens | 1M | 200K |
| Capability score (Epoch Capabilities Index; GPT-5 is 150) | 165 | 150 |
| Longest answer, tokens | 128K | 64K |

## What 8 everyday jobs cost a month on each

Each job at its usual runs a day, for 30 days, at the standard price.

| Job | Tokens in, out, runs a day | Claude Fable 5.1 | Claude Opus 4.5 |
| --- | --- | --: | --: |
| A chat question | 300, 500, 100 | $84.00 | $42.00 |
| A hard question, with thinking | 300, 1,400, 100 | $219 | $110 |
| A long report, summarised | 60,000, 2,000, 20 | $420 | $210 |
| A 40-turn agent task | 2,800,000, 40,000, 10 | $1,629 | $1,098 |
| A support bot's reply | 4,000, 300, 2,000 | $2,130 | $1,110 |
| Sort a message into a category | 250, 5, 50,000 | $4,125 | $2,063 |
| Read an invoice into fields | 1,500, 250, 1,000 | $825 | $413 |
| Review a pull request | 25,000, 4,500, 50 | $713 | $356 |

## Questions

### Which is cheaper, Claude Fable 5.1 or Claude Opus 4.5?

Claude Opus 4.5 is cheaper: $5 per million tokens read and $25 per million written, against $10 and $50 on Claude Fable 5.1. On a mix of 3 tokens read for each 1 written, Claude Fable 5.1 costs 2 times as much.

### Which is better, Claude Fable 5.1 or Claude Opus 4.5?

On the Epoch Capabilities Index, an independent score from Epoch AI that combines over 50 benchmarks, Claude Fable 5.1 scores 165 and Claude Opus 4.5 150, above the top of the range of doubt around Claude Opus 4.5's score (GPT-5 is 150). One score is an average; test both on your own work before you switch.

### What does a support bot cost a month on Claude Fable 5.1 and Claude Opus 4.5?

At 2,000 replies a day, each reading 4,000 tokens (50 percent of them from cache) and writing 300, it costs $2,130 a month on Claude Fable 5.1 and $1,110 on Claude Opus 4.5: Claude Fable 5.1 costs 1.9 times as much for this job.

### What does an AI agent task cost on Claude Fable 5.1 and Claude Opus 4.5?

One 40-turn task that reads 2,800,000 tokens in all, 90 percent of them from cache, and writes 40,000, costs $5.43 on Claude Fable 5.1 and $3.66 on Claude Opus 4.5. At 10 tasks a day that is $1,629 and $1,098 a month.

### Which has the larger context window, Claude Fable 5.1 or Claude Opus 4.5?

Claude Fable 5.1, with 1M tokens against 200K on Claude Opus 4.5. The window holds your instructions, the files you attach, the conversation so far and the answer, all at once.

### Does the same text take the same number of tokens on Claude Fable 5.1 and Claude Opus 4.5?

Yes, both are counted the same way: our lesson "How AI writes", 1,700 words long, is about 2,100 to 3,600 tokens on each.

### Is it cheaper to move from Claude Opus 4.5 to Claude Fable 5.1?

No, it costs more per token: Claude Fable 5.1 charges $10 per million tokens read and $50 written, against $5 and $25 on Claude Opus 4.5, 2 times as much for the same tokens. It pays off only if better answers save more than that, for example in fewer retries.

### Can I pay less on Claude Fable 5.1 and Claude Opus 4.5 for work that can wait?

Yes, on both. With a batch, where you collect the answers later instead of at once, Claude Fable 5.1 costs $5 per million tokens read and $25 written, and Claude Opus 4.5 $2.50 and $12.50.

## Sources

- [Anthropic: API prices](https://platform.claude.com/docs/en/about-claude/pricing)
- [Epoch Capabilities Index, by Epoch AI (CC BY 4.0)](https://epoch.ai/benchmarks/eci)

## Other comparisons

- [Claude Fable 5.1 vs Claude Mythos 5.1](https://tecyfy.com/prices/compare/claude-fable-5-1-vs-claude-mythos-5-1.md)
- [Claude Fable 5 vs Claude Fable 5.1](https://tecyfy.com/prices/compare/claude-fable-5-vs-claude-fable-5-1.md)
- [Claude Fable 5.1 vs Claude Mythos 5](https://tecyfy.com/prices/compare/claude-fable-5-1-vs-claude-mythos-5.md)
- [Claude Fable 5.1 vs Claude Opus 5](https://tecyfy.com/prices/compare/claude-fable-5-1-vs-claude-opus-5.md)
- [Claude Fable 5.1 vs Claude Opus 4.8](https://tecyfy.com/prices/compare/claude-fable-5-1-vs-claude-opus-4-8.md)
- [Claude Fable 5.1 vs Claude Opus 4.7](https://tecyfy.com/prices/compare/claude-fable-5-1-vs-claude-opus-4-7.md)